In recent years, there has been widespread application of electronic devices equipped with touch panels in the display screens thereof. However, extraneous light and reflections cause glare on the surface of these touch panels and affect the visibility of the display. To avoid this, the touch panel film may undergo surface processing known as antiglare processing, whereby the surface of the touch panel is made coarser to scatter light. A method for making the film surface coarser is to coat the film surface with a UV curing resin in which fine particles, known as filler, are dispersed, and then to cure the resin to form a roughness of several microns.
As described for example in Japanese Unexamined Patent Application Publication No. 2004-351744, which is which is incorporated herein by reference in its entirety, a touch panel 2 using this type of touch panel film 1 is configured as shown in FIG. 4. The touch panel 2 is equipped with a touch panel substrate 4, which is a transparent insulative substrate, provided on the front surface of an electronic device liquid crystal display 3. A transparent electrode 7b of ITO (indium-tin oxide) film or the like is provided in a predetermined pattern on the surface of the touch panel substrate 4. Then the touch panel film 1 is attached so as to cover the touch panel substrate 4.
The touch panel film 1 is formed from a film substrate 5 of PET (polyethylene terephthalate) or the like, and on the surface facing the rear surface of the touch panel substrate 4, a transparent electrode 7a of ITO film or the like is provided via an anchor layer 6 at a predetermined spacing of gap g with the transparent electrode 7b of the touch panel substrate 4. Moreover, on the front surface of the film substrate 5 of the touch panel film 1, a filler 8 having a particle size of approximately several microns is affixed with a UV curing resin 9.
However, with the higher resolution of liquid crystal displays in recent years, although the above-described type of antiglare processing with particles of several microns in size is able to suppress reflections and other glare, because light rays from the liquid crystal material have a fine pitch, the filler and roughness thereof cause the light from the liquid crystal to reflect diffusely, creating glare and causing color separation in the liquid crystal pixels, thereby noticeably degrading the visibility of the display.
Thus, Japanese Publication No. 2004-3517441 discloses a touch panel to which antiglare processing is carried out using a filler of fine particles having an average primary particle size of 100 nm or less, forming a ten-point average roughness Rz of at least 100 nm but less than 500 nm.
The prior art disclosed in the Japanese Publication No. 2004-3517441 corresponds to a liquid crystal display having a high resolution known as eXtended Graphics Array (XGA) resolution and a pixel pitch of approximately 123 dpi, but does not provide sufficient effect in suppressing glare and the like for the higher resolution liquid crystal displays of today such as Wide XGA (WXGA) and Super XGA (SXGA) displays having pixel pitches of approximately 0.2/mm.